SU746333A1 - Amplitude-modulated signal modulation factor value converter - Google Patents

Description

(54) CONVERTER OF VALUES OF THE MODULATION FACTOR Amplitude of the BOTTOM MODEL OF THE DIRECTED SIGNAL The invention relates to the measurement technique, can be used when measuring the values of the modulation factor of the amplitude modulated signal. The known modulation factor value converter 1 has a high noise immunity due to the introduction of selective amplifiers that are carrier and optional of the side frequencies. The disadvantages of the known device are the complexity of the technical implementation, due to the need to use high-quality narrow-band filters, as well as the dependence of the follow-up period of the output pulses on the carrier level. A converter is also known that contains synchronous detectors, a differential amplifier and an inverter, with the signal inputs of the synchronous detectors connected to the output of the input amplifier, the output of the carrier amplifier connected to the control input of the first detector and via the inverter with the control input of the second synchronous detector, the outputs of synchronous detectors are connected to the inputs of a differential amplifier, the output of which is connected to the second input of the voltage transformer in the turn of the inverter. A disadvantage of the known device is the dependence of the duration of the output pulses and the period of their following from the carrier level, which necessitates their changing followed by dividing the obtained values, which leads to a limitation of speed and the appearance of additional errors associated with the specified operations. In addition, since the follow-up period of the output pulses and their duration are proportional to the effective values of carrier and envelope voltage, respectively, a preliminary rectification of the input signal and envelope tension, followed by passing them through the low-frequency inertial filter, is necessary.

The inertia of the filters limits the flonycTHKfyK) measurement rate of the input level carrier signal (hch) of the signal when measuring the modulation coefficient.

The aim of the invention is to improve the accuracy of g speed.

The goal is achieved by the fact that in the converter of the modulation factor value of an amplitude-modulated signal containing a voltage converter is a time interval of an input signal amplifier, the output of which is connected to the signal inputs of the Rvogo and second synchronous detectors and through the driver of the control voltage the input of the first synchronous detector and the input of the inverter, while the output of the inverter is connected to the control input of the second synchronous detector, the outputs of the synchronous detectors The ditch is connected to the inputs of the first differential amplifier, the output of which is connected to the input of a pulse detector, the second and third differential amplifiers are introduced, the expander is to the triangular voltage generator, and one of the inputs of the second secondary amplifier is connected to the first output of the first synchronous detector, and the other input - with the second output of the first synchronous detector, the output of the second differential amplifier is connected via a function generator to the first input of the converter, for example Yoni time interval, the first and second inputs of the third differential amplifier connected to the first and second rectifier outputs, whose output is connected to the output of the first differential amplifier, and the output of the third differential amplifier connected to the second input transducer naP1 Sheni -vremeshyuy interval.

FIG. 1 shows the block diagram of the proposed device a; in fig. 2 - stress diagrams for his work.

The device comprises an input signal amplifier i, a control voltage driver 2, an inverter 3, synchronous detectors 4-5, a first and second differential amplifiers 6, a converter 8, a third differential amplifier 9, a function generator 10 of a triangular voltage, 74 6333

the creator of the 11 th voltage-time interval.

The device works as follows.

AM voltage is supplied to the input of amplifier 1 (see Fig. 2, a)

t Bx l Mfi + nSinftOSi-Hcyt, (1) where 1 / c is the amplitude of the unmodulated

load bearing; Cx) is the angular frequency of the carrier; - angular frequency of the envelope; Tg is the modulation coefficient.

From the first output of the synchronous detector 4 to one input of the differential amplifier B, a signal is received that contains the envelope of the input AM signal and a constant component determined by the carrier level (see Fig. 2.6)

g / sd, Kt (mUMSi.n.S2tvirM, (2) where Kj / is the transmission coefficient of the path

device input - output of the synchronous detector 4.

Go the second output of the synchronous detector 4 to the second input of the differential amplifier 6 and the first input of the differential amplifier 7 receives a signal (see Fig. 2, c)

Vgii KtmUni inftt. (3)

The signal at the output of the synchronous detector 5 (see Fig. 2, d)

Uh2 -KimUmSitiS; t, (4)

where K is the path transmission coefficient

the input of the device is the output of the synchronous detector 5. At the output of the differential amplifier 6, a constant voltage is proportional to the level of the carrier (see Fig. 2, e)

U UcAi-IfQi-KiKal / n ,,, (5) where Ke. - the transfer coefficient of the differential amplifier 6. If to ensure equality: To then at the output of the differential amplifier 7 (see. Fig. 2, e)

% Usgl-l g 2KchK mU „, Sln5gt,

where K is the transmission gain of the differential amplifier 7. The signal (7), after being rectified by its rectifier 8, can be written as.

il / al eKHK-fKemll - U t), (8)

where Kg is the transmission coefficient, rectifier 8; I7 (i / - variable component

rectified voltage. If the voltage (8) is applied to one input of the differential amplifier 9, and

supply the variable component etog voltage to another input, including, for example, a separating capacitor between the output of the detector 8 and this input, then at the output of the differential section 9, as a result of algebraic subtraction of the specified voltage

and gkchk KBtTsm (9)

Function generator 10 generates a triangular voltage, the amplitude of which is proportional to the control voltage (5) supplied to its input from the differential amplifier 6, i.e.

VusK.KjKjUMr (10)

where K; j is the coefficient of proportionality between the amplitude of the triangular voltage and the control voltage.

From the function generator 1O, a triangular voltage is applied to the first input of the voltage converter 11, a time interval, to the second input of which a signal (9) is received. In the converter, the instantaneous value of the triangular voltage is compared with the effective value. voltage (9) and the formation of the output pulses of the device {see FIG. 2, well, and).

Claims (1)

1. USSR author's certificate number 42O963, cl. (01 R 29/06, 1975.